Venetian-blind construction for taking up lift-cord slack



E. PREZIOSI VENETIAN-BLIND CONSTRUCTION FOR TAKING UP LIFT-CORD SLACK Filed D90. 24, 1964 2 Sheets-Sheet 1 INVENTOR E/V/Q/CO PRE Z 108/ ATTORN EY I E. PREZIOSI Oct. 25, 1966 VENETIAN-BLIND CONSTRUCTION FOR TAKING UP LIFT-CORD SLACK Filed Dec. 24, 1964 2 Sheets-Sheet 2 QQE 'INVENTCR E/VlQ/CO Pk'EZ/OS/ BY I ATTORNEY United States Patent 3 280 890 VENETIAN-BLIND CO NSTRUCTION FOR TAKING UP LIFT-CORD SLACK Enrico Preziosi, Jersey City, N.J., assignor to Levolor Lorentzen, Inc., Hoboken, NJ., a corporation of New Jersey- Filed Dec. 24, 1964, Ser. No. 420,925 3 Claims. (Cl. 160168) This invention relates to a Venetian-blind construction for automatically taking up lift-cord slack.

Two or more flexible cordlike elements are customarily attached to the bottom bar of a Venetian blind for raising and lowering the blind. I use the term lift cord to designated this flexible cordlike element, regardless of the particular character of the element, and regardless of whether it be made of nonmetallic material or metallic material.

In a reel-type Venetian blind, which is often used Where a blind of larger-than-usual width and height is required, the head bar of the blind is provided with means for reeling and unreeling the lift cords to raise and lower the blind. A blind of this type is disclosed in Lorentzen U.S. Patent 2,250,106 dated July 22, 1941. In that patent the head bar has a hollow shaft which is rotated in one direction to wind the lift cords about it for raising the blind and is rotated in the opposite direction to unwind the lift cords for lowering the blind. By means of a lead screw the shaft is moved longitudinally at each revolution a distance equal to the thickness of the lift cord, whereby the lift cord is wound smoothly on the shaft in a single layer.

In the Lorentzen Patent 2,250,106 the shaft on which the lift cords are wound is manually rotated through a cord drive. However, there are motor-driven blinds of this type, the rotating shaft being driven by a reversible electric motor under the control of a manually operated switch for starting and stopping the motor. Additionally, limit switches have ordinarily been provided to automatically cut off the motor and terminate the raising and lowering of the blind when the upper and lower limits of movement have been reached, as the case may be. It has also been proposed to raise and lower the blind under the control of a thermostat, or under the control of a photoelectric cell.

If the lift cords in a reel-type Venetian blind be no longer than is needed to fully lower the blind the cords will normally be under constant tension due to the weight of the bottom bar and, during normal raising and lowering of the blind, no troublesome slack will develop. However, there are various circumstances under which the tension on one or more of the lift cords will be relieved, with the likelihood that troublesome lift-cord slack will develop.

As the blind is being lowered the bottom bar may strike a pivoted window sash that is standing open, or strike an object sitting on the window sill, with the result that the descent of the bot-tom bar or one end thereof will be arrested while the lift cords are still being unreeled to lower the blind. This will cause slack to develop in one or more of the lift cords; and snarling, jamming and even breakage of a lift cord can result. This is particularly true where the lift cords are metallic wires, either solid or stranded, which have a certain amount of resiliency and spring away from the shafit or reel on which they are wound.

As another example, the blind may have been left in a partially-lowered position and then someone may manually raise the bottom bar or one end thereof to wash the window or get a better view. Again, slack will develop in one or more of the lift cords, with the likelihood of 3,280,890 Patented Oct. 25, 1966 harmful consequences as above referred to. Further, the ladder-and-slait assembly is often made with an excess length of about 1 /2" to insure that, in fully lowered position, the bottom bar will rest on the window sill to exclude light. Then all of the lift cords will be slacked off whenever the blind is fully lowered.

Among the individual objects of the present invention are to provide a Venetian-blind construction for reel-type blinds which automatically takes up lift-cord slack upon one or more of the lift cords being relieved of tension, to provide such a Venetian-blind construction in which the means for taking up the lift-cord slack is concealed Within the bottom bar, to provide such a Venetian-blind construction which can be readily and economically fabricated largely with the use of standard parts, and to provide such a Venetian-blind construction which is simple in structure and reliable in use.

Various other objects and advantages will be apparent from the disclosure herein including the drawings. Sruch disclosure is of the best modes thus far contemplated of carrying out the invention. Neverthless such disclosure is by way of illustration and example only, since the invention may be carried out in other modes, and in some instances it may be unnecessary to accomplish certain objects of the invention.

In both the description and the claims parts at times may be identified by specific names for convenience and ready understanding, but such nomenclature is to be understood as having the broadest meaning consistent with the context and with the concept of the invention as distingu-ished from the pertinent prior art. Except as otherwise indicated, the description hereinafter refers to the particular form or for-ms of the invention shown in the drawing; it does not necessarily refer to any other form in which the invention may be embodied. The claims, however, do embrace other forms in which the invention may be embodied.

FIG. 1 of the drawings is a diagrammatic front elevation of a motor-driven reel-type Venetian blind, parts of the ladders being broken away to reveal the lift cords.

FIG. 2 is a diagrammatic end elevation looking from the right of FIG. 1.

FIG. 3 is a fragmentary front elevation corresponding to the lower portion of FIG. 1 but showing the bottom bar in inclined position, as would result from one end of the bottom bar being arrested by striking a stationary object while the blind was being lowered.

FIG. 4 is a partly diagrammatic top plan view of the bottom bar of the blind with the bottom bar horizontal as in FIG. 1. A large portion of the cover of the bottom bar is broken away to show the interior structure and arrangement.

FIG. 5 is the same type of view as FIG. 4 but corresponding to FIG. 3 in which the bottom bar is tilted.

FIG. 6 is a detail section, in a longitudinal vertical plane, taken as indicated by the line 6-6 in FIG. 4.

FIG. 7 is a detail section in a transverse vertical plane, taken as indicated by the line 7-7 in FIG. 6.

For convenience of illustration an unusually narrow blind is shown. Also, the thickness of sheet material is necessarily exaggerated.

Reference will first be had to FIGS. 1 and 2. These figures show a Venetian blind designated as a whole by 10, in fully lowered position. The blind has a head bar or head designated as a whole by 11 and from which is suspended a ladder-and-slat assembly designated as a whole by 12. The ladder-and-slat assembly is composed of conventional upwardly-crowned metallic-slats 14 which are suspended and articulated together in conventional manner by conventional flexible ladders 15, also called ladder tapes or simply tapes. The ladder-and-slat assembly includes a bottom bar, designated as a whole by 16, which extends along the lower edge of the assembly and to which the lower ends of the ladders are attached.

Spaced along the length of the bottom bar, there are two or more lift cords which extend upwardly from the bottom bar and which are adapted to be pulled in and payed out to raise and lower the bottom bar 16 and thereby raise and lower the blind. The drawings show three such lift cords, designated respectively by 17, 17a and 17b. These lift cords extend upwardly through the ladder-andslat assembly 12 in conventional manner, and into the head .11 for reeling and unreeling by suitable mechanism, eg the mechanism shown in the aforesaid Lorentzen Patent 2,250,106.

As shown diagrammatically in FIGS. 1 and 2 the head 11 is provided with a hollow shaft 19 driven in either direction by a reversible electric motor 20 which may be started and stopped in conventional manner under the control of a manually operated switch. The upper ends of the lift cords are attached to the shaft 19 and are reeled and unreeled by the shaft 19 to raise and lower the blind. If desired, the shaft 19 may be advanced longitudinally with a lead screw as in the aforesaid Lorentz/en Patent 2,250,106 sothat the lift cords will be wound uniformly in a single layer. Conventional limit switches are ordinarily incorporated into the control circuit of the electric motor 20 to cut off the motor when the blind has been fully raised or fully lowered, as the case may be.

The shaft 19 is, of course, horizontal. The motor 20 is mounted with its shaft vertical, and the drive from the motor 28 to the shaft 19 is through a worm and gear contained in gear box 21. With a worm-and-gear drive the blind is automatically held in any raised position in which the motor 20 may be stopped.

FIG. 3 illustrates diagrammatically the condition that will result when the right-hand end of the bottom bar 16 strikes a stationary object and its descent is arrested while the lift cords are being unreeled to fully lower the blind. As shown in FIG. 3 this results in all three lift cords being slacked off, in the amounts indicated by the phantom lines A, B and C.

For lift cords 17, 17a and 17b I have used 16-strand stainless-steel cable having an over-all diameter of approximately This cable has strength adequate for very heavy blinds, while being of such small diameter that a long length of it can be wound in a small space on the shaft 19. Due to the springiness and resiliency of the cable, and in the absence of means for taking up slack, the lift cords will spring away from the shaft 19 when the lift cords are slacked 01f, whether in the manner indicated in FIG. 3 or otherwise. Such springing away of the convolutions would likely have harmful consequences as has been explained.

Reference will now be had to FIGS. 47. The body of the bottom bar 16 is a length of sheet-steel channel 22, which has portions folded upwardly and formed into longitudinally extending ribs 24, 24. These ribs subdivide the interior of the channel 22 into three parallel channel-portions 25, 26 and 27 that extend throughout the length of the bottom bar. The opposite sides 29, 29 of the channel 22 have their upper edges turned inwardly and formed into lips 30, 30 which extend for the length of the channel 22. A slat 14, which is the same as the other slats 14 of the blind, serves as a cover for the channel. This coverslat is telescoped longitudinally into position with the edges of the slat beneath the lips 30, 30 and the center portion of the slat pressed upwardly somewhat by the tops of the ribs 24, 24. Suitable hollow end-caps 31, 31 are telescoped over the opposite ends of the channel 22 and its cover-slat 14.

The bottom-bar channel 22 and the slat-cover therefor are well-known in the trade and are disclosed in Nelson Patent 2,618,329 issued November 18, 1952. Suitable end caps 31 are well-known in the trade also, one suitable end cap being disclosed in Lorentzen Patent Des. 162,192 issued February 27, 1951.

The lower ends of the ladders 15 are fixedly attached to the bottom bar. The attachment may be in any suitable way known to the art, various suitable ways being known. By way of illustration and example, a tape anchor 34 may be used which is of the type disclosed in Anderle US. Patent 2,861,631 issued November 25, 1958. The lower ends of the two vertical side tapes 15a, 15a of each ladder 15 are folded under a tape anchor 34 and are attached to the under side thereof as disclosed in Patent 2,861,631. As is also disclosed in that patent, the tape anchor 34 has laterally-projecting finger-portions which are entered beneath the lips 30, '30 by moving the tape anchor transversely of the channel 22, first in one direction and then in the opposite direction, the anchor 34 being self-latching to the channel to prevent fortuitous disengagement, all as disclosed in said Anderle Patent 2,861,631.

At each lift-cord location, each slat 14 of the blind is provided with a transverse slot, known as a route opening, through which the lift cord passes. The slat 14 which is used as a cover slat for the bottom-bar channel 22 has the same route openings. At the route openings of the cover slat I provide the bottom bar with cord-guiding blocks that are adapted to effect a change of direction of the lift cord. Three cord-guiding blocks are shown in the drawing, being designated as a whole by 36, 36a and 36b, respectively. Block 36 will be described and duplicates thereof may be used as blocks 36a and 36b.

Block 36 has an essentially rectangular body 37 of the length seen in FIG. 6, the width seen in FIG. 7 and the height seen in both FIGS. 6 and 7. The bottom of the body 37 is longitudinally channelled, thereby providing a tunnel 38 which extends for the length of the body 37. Extending upwardly from the center of the body 37 there is a boss 39. This boss projects through the route opening in the cover slat 14 and thence through a corresponding opening in the tape anchor 34, whereby the block is held against movement lengthwise of the bottom bar. As is seen in FIGS. 6 and 7, the body 37 of the block nests within the central channel portion 26 of the bottombar channel 22; and it makes a sliding fit therewith. A vertical bore 40, each end portion of which is flared outwardly, extends upwardly from tunnel 38 and out through the top of boss 39. A diagonal bore 41, for a purpose to be described, extends between the end of the body 37 and the top of the tunnel 33.

A helical tension spring 43 extends longitudinally within the central channel portion 26 of the bottom-bar channel, being located between the cord-guiding blocks 36 and 36b. The lift cord 17 is connected to the left-hand end of the spring 43 and extends longitudinally of the channel portion 26, into the tunnel 38, thence through vertical bore 40, and upwardly through the ladder-and-slat assembly 12 of the blind. The lift cord 17b is connected to the right-hand end of the spring 43 and extends in the opposite direction inv similar manner to cord-guiding block 36b and thence upwardly through the ladder-andslat assembly 12 of the blind.

Each lift cord 17 and 17b may be attached to the spring 43 in the manner shown in FIG. 6 for lift cord 17. As shown in FIG. 6 the lift cord 17 passes through horizontal bores in metal beads 44 and 45, after which it is looped through the eye 46 of spring 43 and back through the horizontal bore of bead 45. Each of the beads 44 and 45 is provided with a set screw, preferably with a hexagonal socket in the top to receive a tool for turning the set screw and making clamping engagement with the lift cord 17. As is seen in FIG. 5, the lift cord 17b is connected to the'right-hand end of the spring 43 in like manner, with the aid of duplicate beads 44 and 45, respectively.

If the lift cords of the blind be no longer than is needed to fully lower the blind, the weight of the bottom bar 16 normally will keep the lift cords under tension. To increase t e amount of the lift-cord tension when the bottom bar is near its lowermost position and has little or no load of slats on top of it, and thereby insure that under normal conditions the weight of the bottom bar will be suflicient for full extension of the helical spring or springs to which the lift cords are connected, I increase the weight of the bottom bar by nesting lengths of rectangular steelbars 47 and 48 into the channel portions 25 and 27 of the bottom-bar channel 22. These lengths of steel bars may extend for the length of the bottom bar or only a portion of the length thereof, according to the increase in weight of the bottom bar that is needed or is desirable.

Under normal conditions the spring 43 is extended by the weight of the bottom bar to the extent permitted by beads 44, 44 striking the cord-guiding blocks 36 and 36b. Upon one or both of the lift cords 17 and 17b being slacked off Within the range of the spring 43, as for example under the condition illustrated in FIG. 3, the spring 43 contracts and takes up the slack. In FIG. 5 take-up indicated by A and B corresponds with the slacking off indicated by A and B in FIG. 3. Upon normal tension being restored to lift cords 17 and 1712, as by the blind being returned to the normal condition illustrated in FIG. 1, the spring 43 returns to the extended position shown in FIG. 4.

Between cord-guiding blocks 36 and 36a there is a second tension spring 49 which is arranged similarly to tension spring 43 and functions in similar manner to take up slack upon lift cord 17a being slacked off. The end of the lift cord 17a is attached to the eye 50 at the lefthand end of the spring 49, in the manner already described in connection with lift cord 17 and spring-eye 46. Where the blind has an odd number of lift cords, as is shown in the drawings, there will be no lift cord to attach to the right-hand end of the spring 49. Therefore the righthand end of spring 49 is anchored to the block 36 by threading the eye-forming convolution 51 through the diagonal bore 41 in block 36.

Various specific procedures may be used for assembling the bottom bar. For example, the lift cords may be brought downwardly through the route openings in the cover-slat 14, thence through the cord-guiding blocks, through the beads 44 and 45 and connected to the helical springs. Then the blocks and springs can be manually held in position as the channel 22 is telescoped onto the cover-slat 14.

It will be seen that, by means of the present invention, automatic slack take-up may be provided for blinds having an odd number of lift cords as well as for blinds having an even number of lift cords.

T'he embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A reel-type Venetian blind comprising:

a ladder-and-slat assembly including a hollow bottom bar extending along the lower edge of the assembly, helical spring means extending longitudinally within the bottom bar,

a plurality of lift cords attached to the helical spring means,

the lift cords extending longitudinally within the bottom bar and thence upwardly therefrom at locations spaced along the length of the bottom bar, the lift cords and the helical spring means normally being tensioned by the weight of the bottom bar, and the helical spring means resiliently taking up slack upon one or more of the lift cords being relieved of tension. 2. A reel-type Venetian blind comprising: a ladder-and-slat assembly including a hollow bottom bar extending along the lower edge of the assembly, two cord guides nested within the bottom bar,

said cord guides being spaced relatively far apart along the length of the bottom bar, and said cord guides, taken together, being adapted to receive a pair of lift cords extending longitudinally within the bottom bar in opposite directions and direct the lift cords upwardly from the bottom bar in spaced relation, a helical tension spring within the bottom bar,

said spring extending longitudinally of the bottom bar and being located between said cord guides, and said spring when contracted having a length Which is small as compared to the spacing of said cord guides, and a pair of lift cords, one attached to each end of said spring,

said lift cords extending in opposite directions to the cord guides and thence upwardly from the bottom bar, said lift cords and said spring being normally tensioned by the weight of the bottom bar, and said spring resiliently taking up slack upon one or both of said lift cords being relieved of tension. 3. A reel-type Venetian blind as in claim 2 in which: the blind has an odd number of lift cords, the bottom bar is provided with a separate cord guide for the odd lift cord, and is also provided with a separate helical tension spring to which the odd lift cord is attached, 7

the odd lift cord and the separate tension spring being normally tensioned by the weight of the bottom bar, and the separate tension spring resiliently taking up slack upon the tension on the odd lift cord being relieved.

References Cited by the Examiner UNITED STATES PATENTS 2,749,976 6/1956 Lewis -173 X HARRISON R. MOSELEY, Primary Examiner.

P. M. CAUN, Assistant Examiner. 

1. A REEL-TYPE VENETIAN BLIND COMPRISING: A LADDER-AND-SLAT ASSEMBLY INCLUDING A HOLLOW BOTTOM BAR EXTENDING ALONG THE LOWER EDGE OF THE ASSEMBLY, HELICAL SPRING MEANS EXTENDING LONGITUDINALLY WITHIN THE BOTTOM BAR, A PLURALITY OF LIFT CORDS ATTACHED TO THE HELICAL SPRING MEANS, THE LIFT CORDS EXTENDING LONGITUDINALLY WITHIN THE BOTTOM BAR AND THENCE UPWARDLY THEREFROM AT LOCATIONS SPACED ALONG THE LENGTH OF THE BOTTOM BAR, THE LIFT CORDS AND THE HELICAL SPRING MEANS NORMALLY BEING TENSIONED BY THE WEIGHT OF THE BOTTOM BAR, AND THE HELICAL SPRING MEANS RESILIENTLY TAKING UP SLACK UPON ONE OR MORE OF THE LIFT CORDS BEING RELIEVED OF TENSION. 